//******************************************************************************************************//  RollingWindow.cs - Gbtc////  Copyright © 2015, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the MIT License (MIT), the "License"; you may//  not use this file except in compliance with the License. You may obtain a copy of the License at:////      http://www.opensource.org/licenses/MIT////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  02/02/2015 - Stephen C. Wills//       Generated original version of source code.////****************************************************************************************************** using System;using System.Collections;using System.Collections.Generic;using GSF.NumericalAnalysis; namespace GSF.Collections{    /// <summary>    /// Represents a rolling window of data with FIFO semantics that will    /// automatically truncate the data when the window size is exceeded.    /// </summary>    /// <typeparam name="T">The type of objects to be stored in the rolling window.</typeparam>    public class RollingWindow<T> : IList<T>    {        #region [ Members ]         // Fields        private int m_windowSize;        private T[] m_window;        private int m_start;        private int m_count;         private int m_version;         #endregion         #region [ Constructors ]         /// <summary>        /// Creates a new instance of the <see cref="RollingWindow{T}"/> class.        /// </summary>        /// <param name="windowSize">The size of the window maintained by the collection.</param>        public RollingWindow(int windowSize)        {            if (windowSize <= 0)                throw new ArgumentOutOfRangeException(nameof(windowSize), "windowSize must be at least 1");             m_windowSize = windowSize;            m_window = new T[windowSize];        }         #endregion         #region [ Properties ]         /// <summary>        /// Gets the number of elements contained in the <see cref="RollingWindow{T}"/>.        /// </summary>        public int Count        {            get            {                return m_count;            }        }         /// <summary>        /// Gets the size of the window maintained by the <see cref="RollingWindow{T}"/>.        /// </summary>        public int WindowSize        {            get            {                return m_windowSize;            }        }         /// <summary>        /// Gets a value indicating whether the <see cref="RollingWindow{T}"/> is read-only.        /// </summary>        public bool IsReadOnly        {            get            {                return false;            }        }         /// <summary>        /// Gets or sets the element at the specified index.        /// </summary>        /// <returns>        /// The element at the specified index.        /// </returns>        /// <param name="index">The zero-based index of the element to get or set.</param>        /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is not a valid index in the <see cref="RollingWindow{T}"/>.</exception>        public T this[int index]        {            get            {                if (index < 0 || index >= m_count)                    throw new ArgumentOutOfRangeException(nameof(index), "index must be greater than zero and less than the size of the collection");                 return m_window[WrapIndex(m_start + index)];            }            set            {                if (index < 0 || index >= m_count)                    throw new ArgumentOutOfRangeException(nameof(index), "index must be greater than zero and less than the size of the collection");                 m_window[WrapIndex(m_start + index)] = value;            }        }         #endregion         #region [ Methods ]         /// <summary>        /// Adds an item to the <see cref="RollingWindow{T}"/>.        /// </summary>        /// <param name="item">The object to add to the <see cref="RollingWindow{T}"/>.</param>        public void Add(T item)        {            if (m_count < m_windowSize)                m_count++;            else                m_start = WrapIndex(m_start + 1);             this[m_count - 1] = item;             m_version++;        }         /// <summary>        /// Inserts an item to the <see cref="RollingWindow{T}"/> at the specified index.        /// </summary>        /// <param name="index">The zero-based index at which <paramref name="item"/> should be inserted.</param>        /// <param name="item">The object to insert into the <see cref="RollingWindow{T}"/>.</param>        /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is not a valid index in the <see cref="RollingWindow{T}"/>.</exception>        /// <exception cref="InvalidOperationException">Rolling window is full (<see cref="Count"/> = <see cref="WindowSize"/>.</exception>        public void Insert(int index, T item)        {            if (index < 0 || index > m_count)                throw new ArgumentOutOfRangeException(nameof(index), "index must be greater than zero and less than or equal to the size of the collection");             if (m_count >= m_windowSize)                throw new InvalidOperationException("Unable to insert item; rolling window is full");             // Increase count first to            // prevent out of range indexes            m_count++;             if (index <= m_windowSize / 2)            {                // Shift left to make room                m_start = WrapIndex(m_start - 1);                 for (int i = 0; i < index; i++)                    this[i] = this[i + 1];            }            else            {                // Shift right to make room                for (int i = m_count - 1; i > index; i--)                    this[i] = this[i - 1];            }             // Insert the item and            // increment the version            this[index] = item;            m_version++;        }         /// <summary>        /// Removes the first occurrence of a specific object from the <see cref="RollingWindow{T}"/>.        /// </summary>        /// <returns>        /// true if <paramref name="item"/> was successfully removed from the <see cref="RollingWindow{T}"/>; otherwise, false.        /// This method also returns false if <paramref name="item"/> is not found in the original <see cref="RollingWindow{T}"/>.        /// </returns>        /// <param name="item">The object to remove from the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>        public bool Remove(T item)        {            int index = IndexOf(item);             if (index >= 0)            {                RemoveAt(index);                return true;            }             return false;        }         /// <summary>        /// Removes the <see cref="RollingWindow{T}"/> item at the specified index.        /// </summary>        /// <param name="index">The zero-based index of the item to remove.</param>        /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is not a valid index in the <see cref="RollingWindow{T}"/>.</exception>        public void RemoveAt(int index)        {            if (index <= m_windowSize / 2)            {                // Shift right to fill space                for (int i = index; i > 0; i--)                    this[i] = this[i - 1];                 this[0] = default(T);                m_start++;            }            else            {                // Shift left to fill space                for (int i = index; i < m_count - 1; i++)                    this[i] = this[i + 1];                 this[m_count - 1] = default(T);            }             m_count--;            m_version++;        }         /// <summary>        /// Determines the index of a specific item in the <see cref="RollingWindow{T}"/>.        /// </summary>        /// <returns>        /// The index of <paramref name="item"/> if found in the list; otherwise, -1.        /// </returns>        /// <param name="item">The object to locate in the <see cref="RollingWindow{T}"/>.</param>        public int IndexOf(T item)        {            int i = 0;             foreach (T obj in this)            {                if (Equals(obj, item))                    return i;                 i++;            }             return -1;        }         /// <summary>        /// Determines whether the <see cref="RollingWindow{T}"/> contains a specific value.        /// </summary>        /// <returns>        /// true if <paramref name="item"/> is found in the <see cref="RollingWindow{T}"/>; otherwise, false.        /// </returns>        /// <param name="item">The object to locate in the <see cref="RollingWindow{T}"/>.</param>        public bool Contains(T item)        {            return IndexOf(item) >= 0;        }         /// <summary>        /// Removes all items from the <see cref="RollingWindow{T}"/>.        /// </summary>        public void Clear()        {            for (int i = 0; i < m_windowSize; i++)                m_window[i] = default(T);             m_count = 0;        }         /// <summary>        /// Copies the elements of the <see cref="RollingWindow{T}"/> to an <see cref="Array"/>, starting at a particular <see cref="Array"/> index.        /// </summary>        /// <param name="array">The one-dimensional <see cref="Array"/> that is the destination of the elements copied from <see cref="RollingWindow{T}"/>. The <see cref="Array"/> must have zero-based indexing.</param>        /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>        /// <exception cref="ArgumentNullException"><paramref name="array"/> is null.</exception>        /// <exception cref="ArgumentOutOfRangeException"><paramref name="arrayIndex"/> is less than 0.</exception>        /// <exception cref="ArgumentException">The number of elements in the source <see cref="RollingWindow{T}"/> is greater than the available space from <paramref name="arrayIndex"/> to the end of the destination <paramref name="array"/>.</exception>        public void CopyTo(T[] array, int arrayIndex)        {            int i;             if ((object)array == null)                throw new ArgumentNullException(nameof(array));             if (arrayIndex < 0)                throw new ArgumentOutOfRangeException(nameof(arrayIndex), "arrayIndex must be greater than zero");             if (m_count > array.Length - arrayIndex)                throw new ArgumentException("Not enough available space in array to copy elements from rolling window");             i = 0;             foreach (T item in this)            {                array[i] = item;                i++;            }        }         /// <summary>        /// Returns an enumerator that iterates through the collection.        /// </summary>        /// <returns>        /// A <see cref="IEnumerator{T}"/> that can be used to iterate through the collection.        /// </returns>        /// <filterpriority>1</filterpriority>        public IEnumerator<T> GetEnumerator()        {            int version = m_version;            int count = 0;             for (int i = m_start; i < m_windowSize; i++)            {                if (version != m_version)                    throw new InvalidOperationException("Collection was modified; enumeration operation may not execute");                 if (count >= m_count)                    break;                 count++;                 yield return m_window[i];            }             for (int i = 0; i < m_start; i++)            {                if (version != m_version)                    throw new InvalidOperationException("Collection was modified; enumeration operation may not execute");                 if (count >= m_count)                    break;                 count++;                 yield return m_window[i];            }        }         /// <summary>        /// Returns an enumerator that iterates through a collection.        /// </summary>        /// <returns>        /// An <see cref="IEnumerator"/> object that can be used to iterate through the collection.        /// </returns>        /// <filterpriority>2</filterpriority>        IEnumerator IEnumerable.GetEnumerator()        {            return GetEnumerator();        }         private int WrapIndex(int index)        {            return (int)Euclidean.Mod(index, m_windowSize);        }         #endregion    }}